Why this matters—now
If heap leach is to become a primary copper route, it needs to act less like a field experiment and more like a controlled reactor.
Today, most heaps are operated with limited visibility — we measure PLS grade, flow, and temperature at the edges, but almost nothing within the ore body itself.
That’s like running a concentrator without instruments.
A new generation of low-cost sensors, model fusion, and Bayesian filtering techniques is changing that.
Together, they make it possible to “see inside” the heap — to infer what’s happening in real time and act before value is lost.
What we can already measure
Modern heaps are beginning to integrate sensor networks that track:
- Moisture & percolation — fibre-optic and TDR probes show where irrigation bypasses or ponds.
- Temperature — distributed thermocouples and fibre Bragg gratings track exothermic reaction zones.
- Gas composition & pressure — oxygen and CO₂ sensors at aeration wells quantify oxidation and air distribution.
- Redox (Eh) & pH — raffinate and intermediate drainage chemistry indicate reaction balance.
- Flow and slope movement — radar and drone LiDAR measure settlement and compaction in real time.
Each dataset is partial, noisy, and location-specific — but when combined through a model-based filter, they create a continuous picture of the heap’s internal state.
From monitoring to state estimation
That’s where data fusion comes in.
By combining sensors with dynamic models (hydraulic + thermal + reactive transport), we can infer unmeasured variables — saturation, oxidant penetration, or reaction progress — across the full heap.
Two techniques are particularly powerful:
- Bayesian updating – probabilistically combines prior model predictions with new sensor data to refine our estimate of what’s happening inside.
- Kalman filtering (and its non-linear variants) – continuously adjusts the model state to match observed data, providing a near real-time picture of heap behaviour.
These are standard in aerospace and process control — and they’re exactly what heap leach needs to transition from “measure once a week” to live decision support.
What this enables
1) Real-time metallurgical balance
Predict extraction and acid consumption continuously instead of waiting for assay lag.
2) Adaptive irrigation & aeration control
Shift flow, pressure, or chemistry dynamically to maintain optimal Eh, temperature, and saturation profiles.
3) Early fault detection
Spot bypassing, flooding, or oxygen starvation days before they show up in copper grades.
4) Evidence-based lift design
Use inferred flow paths and reaction zones to plan stacking, compaction, and aeration in the next lift.
5) Closed-loop optimisation
Feed fused heap data directly into control algorithms or digital twins that drive setpoint changes automatically.
Why now
Three converging trends make this real:
- Sensor economics — fibre optics, MEMS pressure sensors, and wireless nodes have collapsed in cost.
- Edge computing — cheap, low-power boards can run state estimation algorithms on site.
- Open-source modelling — tools like OpenFOAM, Elmer, and PHREEQC now allow high-fidelity physics and chemistry to be integrated into operational systems.
The barrier isn’t technology. It’s integration — connecting the physical sensors, the models, and the decision process.
The shift ahead
Heap leach will remain a complex, semi-natural system — but it doesn’t have to be an opaque one.
The next frontier is model-assisted operations: operators and engineers managing by insight, not by instinct.
When every pad behaves like a monitored, learning reactor, leach becomes predictable, optimisable, and bankable.
What Persephone is developing
- CFD + data fusion frameworks coupling heap physics with live sensors
- Bayesian and Kalman-based state estimators for oxidation front and saturation tracking
- Heap digital twin modules that connect to control systems for scenario and optimisation studies
The goal isn’t another dashboard. It’s a new way of running leach pads — closing the loop between chemistry, flow, and value.
Persephone Resources
We help miners bridge the gap between strategy, technology, and operations — turning emerging science into practical systems that deliver value.